The present invention relates to an equalizer and, more particularly, to a transversal equalizer which is applicable to the intermediate frequency band.
A transversal equalizer is used to equalize propagation distortion of digitally modulated signals in the intermediate frequency (IF) band.
The prior art transversal equalizer is made up of a plurality of delay circuits for sequentially delaying a digitally modulated IF input signal, a plurality of first weighting circuits for respectively weighting the modulated input signal and the real components of output signals of the delay circuits, a plurality of second weighting circuits for respectively weighting the modulated input signal and the imaginary components of the output signals, a first combining circuit for combining the outputs of the first weighting circuits, a second combining circuit for combining outputs of the second weighting circuits, and a third combining circuit for orthogonally combining the outputs of the first and second combining circuits.
In a construction of the type described, the number of inputs to the first or the second combining circuits increases with the number of taps of the equalizer since these are always equal in numbers. A combining circuit with many inputs results in a complicated device that suffers from aggravation of the level loss as well as deterioration of the frequency characteristics. Therefore, as the number of taps increases, the prior art equalizer becomes impracticable.